It looks like you are trying to install the beta version over the public version, or vice versa. If that's correct, there are two options:
- If you do not need the old data in the application (or you have a backup on desktop/in the Cloud), then you need to find the application and delete it for all users of the tablet, if there are several. After that, install the application, public or beta version.
- If you need the old data, then please check which version you have. In MLO go to Settings-> About. If you see the numbers in brackets, then this is a beta version that can only be updated to the latest beta.